Genesis and failure of quick clays

Research Project, 2023 – 2026

Clays are ubiquitous materials. The natural clay deposits range from soft sediments with water-filled pores to shale formations that contain hydro-carbons. Arguably, the most elusive naturally occurring clay is quick clay. Upon mechanical perturbation a quick clay irreversibly changes from a solid geomaterial that resists mechanical stress into a liquid. Consequently, quick clays are a major natural hazard and problematic soils for geotechnical engineering. The structure of quick clay is hierarchical and arises from the evolving geological processes between the sedimentation and the current conditions. Although the factors that influence the likelihood of encountering quick clay have been previously studied, the underlying physico-chemical processes that lead a clay to be quick are largely unknown, and not experimentally validated. Furthermore, the micro-structure and processes at grain scale that lead to the solid-liquid transition when disturbed, are yet to be quantified. This project will investigate experimentally the genesis and failure of quick clay by combining physical model tests at elevated stress levels, rheology experiments and miniature hydro-mechanical testing with simultaneous 4D monitoring of the internal structure using optical and X-ray based scattering and imaging methods. The results will be a major contribution to the understanding of the evolving hierarchical material structure that underpins the genesis and failure of natural sensitive clays.